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Desperate Double - RO & comments

Posted By: Karol Szczerek
Date: Saturday, 8 September 2018, at 6:33 a.m.

In Response To: Desperate Double (Karol Szczerek)

OTB I had doubts whether my hits are decisive enough, but there are many shots and some of them are double shots and giving a 4-cube is always stronger than 2-cube (Bob Koca will probably point out a counterexample in a minute, so I should probably say "usually") so finally I shipped it.





White is Player 2

score: 9
pip: 100
13 point match
pip: 122
score: 1

Blue is Player 1
XGID=--BB-bCBB---aC---a-bbbabbA:1:1:1:00:1:9:0:13:10
Blue on roll, cube action?

Analyzed in Rollout No redouble Redouble/Take
Player Winning Chances: 30,86% (G:8,16% B:0,29%) 30,58% (G:8,22% B:0,32%)
Opponent Winning Chances: 69,14% (G:42,67% B:0,36%) 69,42% (G:41,67% B:0,15%)
Cubeless Equities -0,594 -0,190
Cubeful Equities
No redouble:-0,326 (-0,136)±0,009 (-0,335..-0,317)
Redouble/Take:-0,190±0,010 (-0,200..-0,180)
Redouble/Pass:+1,000 (+1,190)
Best Cube action: Redouble / Take
Rollout details
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100,0%
Take Decision confidence:100,0%
Duration: 6 minutes 34 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Compare to 2-cube at -2/-12:





White is Player 2

score: 11
pip: 100
13 point match
pip: 122
score: 1

Blue is Player 1
XGID=--BB-bCBB---aC---a-bbbabbA:0:0:1:00:1:11:0:13:10
Blue on roll, cube action?

Analyzed in Rollout No double Double/Take
Player Winning Chances: 31,13% (G:7,92% B:0,33%) 30,92% (G:7,82% B:0,31%)
Opponent Winning Chances: 68,87% (G:44,77% B:0,52%) 69,08% (G:40,85% B:0,09%)
Cubeless Equities -0,907 -0,818
Cubeful Equities
No double:-0,748±0,008 (-0,756..-0,740)
Double/Take:-0,818 (-0,070)±0,009 (-0,827..-0,810)
Double/Pass:+1,000 (+1,748)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 3,7%
Rollout details
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Double Decision confidence:100,0%
Take Decision confidence:100,0%
Duration: 7 minutes 03 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Look at how different the evaluation (XGR++) at -4/-12 with the cube at 2 vs -2/-12 with the cube at 1 is after some of the hits. With the cube at 2 the market loosers are quite massive I'd say.

After [32]: B/22* 13/11 and [43]: B/21 8/5.
White is Player 2

score: 9
pip: 115
13 point match
pip: 117
score: 1

Blue is Player 1
XGID=--BBabCBB--AaB-----bcbAbb-:1:1:1:00:1:9:0:13:10
Blue on roll, cube action?

At -4/-12 with cube at 2 (shown above).

Analyzed in XG Roller++ No redouble Redouble/Take
Player Winning Chances: 56,30% (G:10,36% B:0,29%) 56,95% (G:10,40% B:0,27%)
Opponent Winning Chances: 43,70% (G:14,61% B:0,45%) 43,05% (G:15,55% B:0,53%)
Cubeless Equities +0,149 +0,934
Cubeful Equities
No redouble:+0,649 (-0,285)
Redouble/Take:+0,934
Redouble/Pass:+1,000 (+0,066)
Best Cube action: Redouble / Take

At -2/-12 with cube at 1 (not shown).

Analyzed in XG Roller++ No double Double/Take
Player Winning Chances: 56,85% (G:10,13% B:0,28%) 57,01% (G:10,30% B:0,29%)
Opponent Winning Chances: 43,15% (G:15,59% B:0,51%) 42,99% (G:15,67% B:0,53%)
Cubeless Equities +0,021 +0,355
Cubeful Equities
No double:+0,317 (-0,038)
Double/Take:+0,355
Double/Pass:+1,000 (+0,645)
Best Cube action: Double / Take

After [32]: B/22* 13/11 and fan.
White is Player 2

score: 9
pip: 122
13 point match
pip: 117
score: 1

Blue is Player 1
XGID=a-BB-bCBB--AaB---a-bbbAbb-:1:1:1:00:1:9:0:13:10
Blue on roll, cube action?

At -4/-12 with cube at 2 (shown above).

Analyzed in XG Roller++ No redouble Redouble/Take
Player Winning Chances: 69,91% (G:24,74% B:0,83%) 68,19% (G:27,44% B:1,01%)
Opponent Winning Chances: 30,09% (G:7,57% B:0,16%) 31,81% (G:10,88% B:0,37%)
Cubeless Equities +0,657 +2,089
Cubeful Equities
No redouble:+1,066
Redouble/Take:+2,089 (+1,023)
Redouble/Pass:+1,000 (-0,066)
Best Cube action: Too good to redouble / Pass
Percentage of wrong take needed to make the double decision right: 6,1%

At -2/-12 with cube at 1 (not shown).

Analyzed in XG Roller++ No double Double/Take
Player Winning Chances: 71,04% (G:22,72% B:0,74%) 69,72% (G:25,49% B:0,90%)
Opponent Winning Chances: 28,96% (G:6,72% B:0,15%) 30,28% (G:8,74% B:0,24%)
Cubeless Equities +0,543 +1,320
Cubeful Equities
No double:+0,855 (-0,145)
Double/Take:+1,320 (+0,320)
Double/Pass:+1,000
Best Cube action: Double / Pass


After [53]: B/22* 22/17* and [42]: B/21.
White is Player 2

score: 9
pip: 135
13 point match
pip: 114
score: 1

Blue is Player 1
XGID=a-BBabCBB---aC---A-bbb-bb-:1:1:1:00:1:9:0:13:10
Blue on roll, cube action?

At -4/-12 with cube at 2 (shown above).

Analyzed in XG Roller++ No redouble Redouble/Take
Player Winning Chances: 75,92% (G:31,70% B:1,08%) 74,31% (G:35,21% B:1,31%)
Opponent Winning Chances: 24,08% (G:5,49% B:0,17%) 25,69% (G:8,40% B:0,33%)
Cubeless Equities +0,882 +2,652
Cubeful Equities
No redouble:+1,220
Redouble/Take:+2,652 (+1,432)
Redouble/Pass:+1,000 (-0,220)
Best Cube action: Too good to redouble / Pass
Percentage of wrong take needed to make the double decision right: 13,3%

At -2/-12 with cube at 1 (not shown).

Analyzed in XG Roller++ No double Double/Take
Player Winning Chances: 77,27% (G:29,11% B:0,97%) 76,12% (G:32,78% B:1,18%)
Opponent Winning Chances: 22,73% (G:3,45% B:0,08%) 23,88% (G:5,84% B:0,12%)
Cubeless Equities +0,772 +1,796
Cubeful Equities
No double:+1,074
Double/Take:+1,796 (+0,722)
Double/Pass:+1,000 (-0,074)
Best Cube action: Too good to double / Pass
Percentage of wrong take needed to make the double decision right: 9,3%

I guess it's probably easy to see once you are able to make doubling window calculations OTB as John provided (thanks John for a great analysis!). I'm not sure I could though. So I'll just remember that offering a 2-cube needs more decisive jokers than when offering the 4-cube. A 4-cube is much stronger when behind so the market loosers tend to be quite huge. One should be not that excited about offering a desperate 2-cube vs a 4-cube.

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